The basement of Technological Institute resembles a tunnel. To each side, wall-length white gates line the sides of the room, showing tanks through small holes in the gates. Beyond a locked door, one large tank contains water that runs into three different tanks, each resembling a stream.

The streams were created to simulate sections of naturally-occurring bodies of water by Kimberly Gray, a civil and environmental engineering professor. The artificial streams are part of a research project studying the effects of denitrification in natural rivers and streams.

Each tank is found in a long and narrow room in the basement level, under the A-Wing hall. The tanks rest on top of large tables, as water streams down from a tube connected to one end of the tank. The water runs alongside the length of the tank and is recirculated to a larger tank, where the water from each of the three artificial streams meets.

Inside each of the tanks – which are about eight meters long and one meter wide – algae and other plant life reside, growing on top of plastic nets placed there by Gray’s team of research assistants.

Two large circular lamps hang over the tanks, simulating sunlight.

“It’s a controlled experiment in a lab,” Gray said. “We sort of operate them as three individual streams.”

Conditions in each plastic-contained stream are adjusted to resemble a wetland, a river and a stream, said Lisa Marx, a McCormick senior who has worked on this and similar research experiments through the environmental engineering department.

“What’s great (about the stream) is that you can control different variables,” Marx said. “You can control light intensity, the amount of nutrients they receive, flow rates of water and water temperature.”

Denitrification in rivers and stream occurs when excess nitrate, found in fertilizers used by farmers, makes its way into streams that run off into large deltas. The nitrate causes a algae growth, depleting the area’s oxygen level, Gray said.

Midwestern farmers contribute to the excess of nitrates because streams and rivers, such as the Sheboygan and Fox rivers in Wisconsin, run from their farms into the Mississippi River and flow into the Gulf of Mexico. This lowers the level of oxygen and kills fish, Marx said.

Gray brought the stream system with her when she began teaching at Northwestern in 1995, but because the tanks are large, finding a suitable space for the tanks in Tech proved difficult.

“Tech has a space crunch, and I had no idea it was going to go,” Gray said. “It took me two years to get the system built.”

McCormick senior David Zorn began working with the streams in spring 2005, helping put together the experiment during its first stages.

“The majority of the research I did with the experiment was to determine the shapes of the nets we put in the tanks,” Zorn said.

After Gray’s team constructed the river and it began running, he spent most of his time doing “maintenance work,” which included making sure the lights continued to work and putting algae food in the tanks.

Reach Marcy Miranda at [email protected].